PUBLICATIONS--Supplement to the computer program documentation for modeling three-dimensional ground-water systems, distributed as Memorandum No. 76.05.


             UNITED STATES DEPARTMENT OF THE INTERIOR
                         GEOLOGICAL SURVEY
                      RESTON, VIRGINIA  22092

                                               October 15, 1976

GROUND WATER BRANCH TECHNICAL MEMORANDUM NO. 77.02

Subject:   PUBLICATIONS--Supplement to the computer program
                         documentation for modeling three-
                         dimensional ground-water systems,
                         distributed as Memorandum No. 76.05.

The attached open-file report by P. C. Trescott and S. P. Larson
entitled, "Supplement to Open-file Report 75-438, Documentation of
finite-difference model for simulation of three-dimensional
ground-water flow" and published as U. S. Geological Survey Open-
file Report 76-591 expands on the discussion in the documentation
in Open-file report 75-438 regarding modeling of layered aquifer
systems.  Corrections to the code and text of the earlier
documentation are also given in the supplement.  Please bring this
publication to the attention of all district and project personnel
concerned with modeling ground-water systems.



                              (s) Charles A. Appel
                              for Chief, Ground Water Branch
                              Water Resources Division

Enclosure

WRD Distribution:   A, B (Limited), FO-L, SL (Subdistrict
Offices), S (w/o attach.)